1. Technical Field
This application generally relates to computer systems, and more particularly to computer system performance.
2. Description of Related Art
Computer systems may include different resources that may be used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as the Symmetrix(trademark) family of data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. An example data storage system may include one or more data storage devices, such as those of the Symmetrix(trademark) family, that are connected together and may be used to provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations, such as data read and write operations and also administrative tasks, such as data backup and mirroring operations. In connection with the I/O operations, a data storage system may include a data storage optimizer used in connection with improving device performance. The data storage optimizer may perform a variety of tasks, for example, determining what logical volumes (LVs) may be candidates for swapping to increase performance of the data storage system in accordance with one or more predetermined criteria. A xe2x80x9cswap planxe2x80x9d, as may be produced by a data storage optimizer, may identify LVs having data included therein to be swapped, and propose a rearrangement of these LVs. It should be noted that the LVs and their data may be swapped in accordance with the swap plan.
Generally, LV candidates may be identified using different techniques, which when rearranged according to the xe2x80x9cswap planxe2x80x9d, are expected to contribute to the reduction of any imbalance of load requirements for a plurality of physical disk storage devices. These different techniques may determine pairs of LV candidates in accordance with a variety of statistics and device-related characteristics, such as, for example, LV size, and device activity. Once these two logical volumes in a pair have been identified, the logical volumes and data are xe2x80x9cswappedxe2x80x9d into their new locations.
One technique used in performing the actual swapping process of the data for each LV and the physical location of each LV includes using a temporary storage area for each LV. Another technique includes using a temporary storage area only for each LV which does not have sufficient redundancy in the data storage system. In one embodiment, this redundancy may be achieved by an LV having three or more copies of its data maintained in the data storage system. One problem is determining a temporary storage area for each LV since each temporary storage area used may have to meet certain predetermined criteria, for example, such as size, that may vary with each LV. Determining whether there are enough temporary storage areas, and determining a temporary storage area for each LV may be used with great frequency, for example, in an optimizer of a data storage system. Thus, it may be desirous to have the technique to be efficient, and extensible for use with increasing numbers of LVs without having performance degradation penalties.
Thus, it may be desirous and advantageous to have an efficient and improved technique for determining whether there is a sufficient number of storage areas for the LVs that need them and for determining a matching temporary storage area for each LV.
In accordance with one aspect of the invention is a method executed in a computer system for determining there are sufficient alternate storage locations and matching at least one logical volume with a unique alternate storage location. The at least one logical volume and at least one alternate storage location are each represented as vertices in a graph. It is determined which of said at least one alternate storage location are candidates for each of said at least one logical volume and a relationship between said each logical volume and each of said at least one alternate storage location is represented as an edge in said graph. Using a bipartite graph matching technique for each of said at least one logical volume, a unique one of said at least one alternate storage location is determined.
In accordance with another aspect of the invention is a computer program product for matching at least one logical volume with a unique alternate storage location. The computer program product includes machine executable code for representing each of said at least one logical volume and each of at least one alternate storage location as vertices in a graph; machine executable code for determining which of said at least one alternate storage location are candidates for each of said at least one logical volume and representing a relationship between said each logical volume and each of said at least one alternate storage location as an edge in said graph; and machine executable code for determining, using a bipartite graph matching technique for each of said at least one logical volume, a unique one of said at least one alternate storage location.